Catalytic olefin metathesis has transformed chemical synthesis and offers exceptionally efficient pathways for synthesis of alkenes. Among various types of olefin metathesis, cross-metathesis of two different terminal alkenes, a reaction that generates only the easily removable ethylene as the side-product, constitutes a remarkably attractive and efficient strategy for synthesis of disubstituted alkenes. Cross-metathesis, however, is a mechanistically complicated variant of this class of transformations. In ring-closing metathesis, reacting alkenes are tethered and the intramolecular reaction is favored; in ring-opening metathesis, release of strain typically serves as the driving force that results in one of several pathways to be preferred. In contrast, cross-metathesis demands that two different alkenes react without the entropic benefit of an intramolecular reaction or strain release, and under conditions that can also cause homo-coupling of the cross partners.
A great number of commercially important molecules contain olefins. Such specialty chemicals include biologically active molecules, oleochemicals, renewables, fine chemicals, and polymeric materials, to name a few. Moreover, many reactions in organic chemistry require alkenes as starting materials. Accordingly, there remains an unmet need for improved methods and catalysts for metathesis reaction.